The machining center has hitherto been used which is arranged to extract and deliver an appropriate tool depending on the machining step from a multiplicity of tools stored in a tool magazine, to thereby change a spindle tool for the delivered one to machine a workpiece. The productivity of the machining center has been enhanced by e.g., increasing the tool change speed.
The tool change is effected by an automatic tool changing apparatus 101 as shown in FIG. 13.
The tool magazine is designated at 103 and comprises a multiplicity of tool pots 103b acting as tool holding means which are linked to an endless chain 103a and individually store various types of tools 105. A standby pot 109 acting as the tool holding means is interposed between the tool magazine 103 and a spindle 107 so that a tool 105a can be held in proximity to the spindle 107.
A tool shifter 111 is disposed laterally of the tool magazine 103 to deliver a tool from the tool magazine 103 to the standby pot 109 and vice versa. An automatic tool changer (ATC) 113 is provided between the standby pot 109 and the spindle 107 to change a tool 105b of the spindle 107 for the tool 105a held by the standby pot 109.
In such an automatic tool changing apparatus 101, during the machining of the workpiece, a used tool is returned from the standby pot 109 to the tool magazine 103 and a tool to next be used is delivered from the tool magazine 103 for preparation in the standby pot 109 so that the tool change time is reduced with a shortened work interruption time to thereby improve its productivity.
In the event that the tool change cycle is short as a result of brief machining steps in succession, however, delivery of the tool to next be used to the standby pot 109 may delay, resulting in a wait for delivery of the tool, which may impair its productivity.
According to the present invention, there is provided an automatic tool changing apparatus comprising a tool magazine which stores a multiplicity of tools each held by tool holding means, the tool magazine having a tool port through which the tools are loaded into or unloaded from the tool magazine; a tool shifter which is provided laterally of the tool port, the tool shifter translating the tools for loading into or unloading from the tool magazine; a standby magazine which has tool holding means by which the tools loaded or unloaded by the tool shifter are temporarily held and stand by; and an automatic tool changer which is arranged to change the tool held in the standby magazine for the tool fitted to a spindle, the tool shifter translating the tools for delivering operations between the tool magazine and the standby magazine, the automatic tool changer also translating the tools for delivering operations between the standby magazine and the spindle, wherein the standby magazine has a plurality of the tool holding means which are provided on an output shaft of a rotation indexing mechanism and which come to rest at respective delivery positions to/from the tool shifter and the automatic tool changer, and wherein the tool holding means of the standby magazine are provided to hold the tool such that the axis of the tool held thereby tilts at a predetermined angle relative to the rotational axis of the output shaft so that the direction of axis of the tool upon the translation by the tool shifter is different from the direction of axis of the tool upon the translation by the automatic tool changer.